package 排序字母2118;

import java.util.Arrays;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		String s=scanner.nextLine();
		char[] ch=s.toCharArray();
		Arrays.sort(ch);
		String set=new String(ch);
		System.out.println(set);
	}
}
